Basalt particles have been investigated as a novel additive for the production of glass fibre reinforced composite using sheetmouldingcompound (SMC) method. Compared to the CaCO
3that are widely used as filler in the SMC composite, the resulting composites
exhibit improved mechanical properties. The tensile strength increased by approximately 15%, whereas the flexural strength wasenhanced by 8% in SMC composites prepared by basalt particles. Examination of the surfacemorphology and interfacial debondingof the specimens is also performed via scanning electron microscopy. Superior strength properties are observed in the basaltparticle-reinforced composites compared to those with the CaCO
3fillers.
1. Introduction
Polymer composites are composed of an inorganic reinforce-ment and a polymericmatrix, providing the desired combina-tion ofmechanical, chemical, and thermal resistance features.Due to its distinct advantages such as design flexibility,dimensional stability, consolidation of parts, high strength,light weight, moderate tooling and finishing costs, and cor-rosion resistance, sheet moulding compound (SMC) is oneof the widely used composite preparation methods.The SMCmethod is a sheet of ready-to-mould composites containinguncured thermosetting resins and uniformly distributedshort fibres and fillers. Commonly, glass fibre is used as areinforcementmaterial and unsaturated polyester as amatrix,along with various fillers and additives in the prepreg formu-lation. Calcium carbonate (CaCO
3) is cheap and easily avail-
able filler and thus is the most widely used filler in the com-posite preparation. Due to its high surface energy, the CaCO
3
reduces mechanical properties of the composite materials [1].Basalt is a rigid, hard, and durable volcanicmineral which
is dark grey or black in colour. It consists of approximately50% SiO
2basalt and originated from the solidification of hot
magma flows rising from volcanoes or cracks in the earth’s
crust. Recently, basalt fibre is used as an alternative reinforce-ment material, which exhibits exceptional characteristics andmechanical properties compared to those of glass fibres.Basalt-polymer materials are primarily used in building con-struction, and then they began to be employed in the auto-mobile, machine, and aerospace industries as a replacementfor traditional glass and carbon fibre reinforcements [2–5].Moreover the basalt fibre is fire resistant and forms insulationagainst sound and heat and thus presents a more economicalalternative to the carbon fibre. For instance, the choppedbasalt fibre can also be mixed with cement to provide bothlower weight and higher structural strength [6–8]. Similarly,basalt particles have also been used as fillers for polymer com-posites. An important feature of the basalt particle is its suit-ability for the moulding process. By adding basalt particlesat a specific rate into the polymer matrix the correspondingcomposites were produced viamoulding.The various proper-ties of these materials involving wear, mechanical properties,and chemical resistance are remarkably enhanced and nobubbles or pores were observed in the structure [9, 10].
A novel strategy has been developed to improve thefibre reinforced composite properties by introduction ofadditional particles in the polymer matrix. For example, the
Hindawi Publishing CorporationInternational Journal of Polymer ScienceVolume 2016, Article ID 1231606, 6 pageshttp://dx.doi.org/10.1155/2016/1231606
2 International Journal of Polymer Science
Table 1: Chemical compositions of basalt particle [12].
Compound Weight percentage in basalt (%)SiO2
51.6–57.5Al2O3
16.9–18.2CaO 5.2–7.8MgO 1.3–3.7Na2O 2.5–6.4
K2O 0.8–4.5
Fe2O3
4.0–9.5
mechanical properties of carbon fibre reinforced epoxy com-posites have been enhanced by the addition of graphenenanoparticles, which enhance the interface mechanics viachemical bonding [11]. In another study, Ary Subagia etal. examined the effect of different tourmaline micro/nano-particle fillers in basalt fibre reinforced epoxy compositesproduced via vacuum-assisted resin transfer moulding. Withthe addition of the particles, the composites gained increasedtensile and flexural properties [2].
In this study, a comparative study for the SMC compositesprepared with glass fibre reinforced composite containingeither CaCO
3or basalt particles has been reported based on
their microstructure and mechanical properties. The com-posites produced from basalt particles had better mechanicalproperties compared with CaCO
3particle-reinforced SMC
composites. The mechanical properties of the specimensare investigated in accordance with the standard tests. Thesurface morphology of the specimens is examined in moredetail via scanning electron microscopy.
2. Materials and Methods
2.1. Materials. The basalt particle is purchased from Basaltex(Masureel Group, Belgium) and its chemical composition isgiven in Table 1.
The E-glass fibre with bundle diameters of 15 𝜇m isprovided byCamElyaf A.S. (SMC3-2400) and cut into 65mmlength and added into resin randomly at a concentration of20% by weight. For the unsaturated polyester resin, Polipol�347-BMC-SMC (Poliya, Istanbul, Turkey) is used in theexperiments, and the resin properties are given in Table 2.
2.2. Preparation of SMC Composites. The SMC compositesare produced in two steps. In the first step, the prepregformulation is prepared according to a given formulation(Table 3) and is incubated for a maturation period (Figure 1).This time period plays a vital role in the bonding betweenthe resin and the fibre. Hence, this bonding also affects themechanical properties of the composite material.
In the second step, the SMC plates were retained in a spe-cially prepared 140 × 280mm2 sheet mould at temperaturesof 140–150∘C under the effect of 80-bar constant pressure forabout 4min (Figure 2).
2.3. Characterization. A diamond saw is used to cut themanufactured plates and the specimens are prepared accord-ing to ISO527 and ISO178, respectively, for tensile and
Table 2: Polyester resin properties.
Property ValueDensity 1.118 gr/cm3
Tensile strength 52MPaFlexural strength 117MPaElongation at break 3.86%
flexural strength tests. The tensile tests are performed withthe Shimadzu-AG-I machine at a speed of 5mm/min andthe flexural tests are done using the Zwick-1446 machine(Figure 3) at 2mm/min.
The morphological features of the broken compositesurfaces obtained from the tensile and flexural tests arecharacterized by SEM (Carl Zeiss EVO 40) with acceleratingvoltage of 20 kV. The specimen surfaces are coated with goldpalladium and observed under reduced pressure.
3. Results and Discussion
The strength of the composite materials is directly relatedto the interfacial mechanics between matrix and fibre. Theinterface strength increases the composite material strength.In recent years, some attempts have been made to improvethese chemical and mechanical bonds. The particle additivesare usually aimed at reducing the cost, but the chemical andphysical properties of composite materials featuring particlesproduced with additives are also improved. Basalt fillers areused in road construction and, in mineral form, for heatand sound insulation. As a reinforcing filler material, it isused in composites where improved mechanical propertiesare desired. Moreover, it is also used to improve wearand corrosion resistance. In this study, the specimens wereproduced with basalt particles instead of the commonlyused CaCO
3filler and the mechanical properties of these
new composite materials were investigated. The specimenswere broken using testing equipment according to standardprocedures, as shown in Figure 4.
Generally, glass fibre provides the greatest strength whenused as the reinforcement material in SMC composites,whereas the CaCO
3fillers are useful to tune the paste
viscosity and reduce the cost. The main purpose of thisstudy is to improve the mechanical properties of SMCcomposites through the improvement of matrix propertiesby the addition of basalt particles instead of CaCO
3fillers.
The replacement of CaCO3fillers with basalt particles brings
Figure 2: (a) SMC plate containing CaCO3filler in the mould and (b) SMC plate containing basalt filler.
(a) (b)
Figure 3: The specimens fixed the testing device (a) tensile and (b) flexural tests.
(a) (b)
Figure 4: Broken test specimens, (a) filled with CaCO3and (b) filled with basalt particles.
4 International Journal of Polymer Science
0 1 2 3 40
10
20
30
40
50
60
70
80
90
R-65-1R-65-2R-65-3
R-65-4R-65-5
Strain (%)
Stre
ss (N
/mm
2)
(a)
0 1 2 3 4 5 6
0
20
40
60
80
100
BP-R65-1BP-R65-2BP-R65-3
BP-R65-4BP-R65-5
Strain (%)
Stre
ss (N
/mm
2)
(b)
Figure 5: Tensile strength values of composite materials filled with CaCO3(a) and basalt particles (b).
0 1 2 3 4−10
0
10
20
30
40
50
60
70
80
Strain (%)
BP-R65R65
Stre
ss (N
/mm
2)
Figure 6: Sample tensile strength values of a specimen.
many outstanding features such as being fire resistant,explosion-proof, andnontoxic andnot reactingwith the air orwater in the matrix. Both tensile and flexural tests confirmedthat the SMC composite prepared by basalt fillers has bettermechanical properties compared to the composite containingCaCO
3fillers. Without changing the reinforcement material
(glass fibre), this increase in the mechanical properties bysimplematrixmodification is a significant finding.The tensileand flexural test results can be found in Figures 5 and 6. Thetensile strength increased by approximately 15%, whereas theflexural strength was enhanced by 8% (Figure 7).
In the literature, the failure mechanism of compositematerials is usually explained in three stages. In the first stage,microcracks are formed in the matrix, followed by fibre-matrix debonding and interfacial decohesion and eventually
Tensile Flexural0
40
80
120
160
200
240
280
BP-R65R-65
R-65BP-R65
Stre
ss (N
/mm
2)
SampleTensile Flexural
Value St. dev. Value St. dev.67.58 7.02 153.49 8.6177.98 5.91 165.93 6.82BP-R65
R-65
(N/mm2) (N/mm2)
Figure 7:The average values for tensile and flexural strength valuesof R-65 and BP-R65 test specimens.
by fibre breakage [13–17]. In our case, the basalt particles notonly prevent the microcracks of the final composites but alsoimprove the cohesion between glass fibre andmatrix; thus themechanical properties of SMC composites are significantlyenhanced. The average tensile and flexural strength valuesobtained with samples using CaCO
3and basalt fillers are
given in Figure 7.This graphic shows that an increment trendin both tensile and flexural stress is obtained.
The morphology of SMC composites is also investigatedby SEM equipment using fracture surfaces of the tensile andflexural specimens. In the CaCO
3filled SMC composite, it
can be observed enveloping the fibre surface in Figure 8and reducing the interfacial strength between the fibre andmatrix. Due to insufficient interface strength, the pull-out of
International Journal of Polymer Science 5
Pull-out
Debonding
Figure 8: The SEM images of the SMC composite filled with CaCO3.
Figure 9: The SEM images of SMC composite filled with basalt particles.
glass fibre easily occurred in the matrix. Consequently, theinterfacial debonding results in a decrease in both tensile andflexural strengths.
On the other hand, in the case of basalt particle-reinforced composite, the basalt particles help to hold theglass fibre together with matrix in the composite (Figure 9).Thus, the formation ofmicrocracks in thematrix particles hasbeen relatively delayed in the first stage of damage. Hence,the mechanical properties of the SMC plates are remarkablyimproved and the failure mechanism has been deferred.
4. Conclusions
In conclusion, basalt particles as an alternative filler forglass fibre reinforced SMC composite has been investigated.Compared to the CaCO
3fillers that are generally used in
the SMC composite, the basalt particles filled sample exhibitssignificant improvement on the tensile and flexural strengths.The morphologies of the obtained SMC materials are inves-tigated by SEM analysis. In the CaCO
3filled composites,
fibre pull-out and interfacial debondingmore easily occurreddue to the high surface energy. This could be responsible forreducing themechanical properties of the nonpolar matrices.Conversely, the basalt particles hold glass fibre and matrixtogether and resulted in improved strength properties. In thefuture studies, the proportion of basalt fillers and new SMCproduction methods will be examined in order to achievebetter mechanical properties.
Competing Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper.
Acknowledgments
This paper is based upon work supported by Uludag Uni-versity (Research Grant no. UAP(M) 2011-29). The authorsare grateful to Dr. Mehmet Atilla Tasdelen from YalovaUniversity Polymer Engineering Department for his valuablecontributions.
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